Data used for the study were received by the California Preterm Birth Initiative at the University of California San Francisco by June 2016.Not only did the risk models differ by residence within Fresno County, but the percentage of women with the risk varied greatly for some factors. In urban residences, 12.2% of women with preterm births smoked, while 6.6% of women in rural residences with preterm birth smoked. Similarly, 8.9% of urban women with a preterm birth used drugs or alcohol and 4.4% women in rural residences with preterm birth did. Nearly five percent of urban women delivering preterm had fewer than three prenatal care visits and 2.3% of women in suburban residences had this few number of visits. The percent of women with a preterm birth and with interpregnancy intervals less than six months ranged from 7.7%to 11.2%. When examining these risk factors in more geographic detail, appropriate targets for preterm birth reduction are elucidated. For instance, in six census tracts 15% or more mothers of preterm infants smoked during their pregnancy – four in urban residences and two in suburban residences . Also, five census tracts in urban residences show that over 10% of mothers who delivered preterm used drugs or alcohol . Over 2,600 women delivering in Fresno County had a cumulative risk score for preterm birth ≥ 3.0: 2.2% of women living in urban residences, 4.1% in suburban,cannabis equipment and 3.7% in rural residences had this high risk score . In this study of preterm births in Fresno County, we found that differences in the type and magnitude of risk and protective factors differed by the residence in which women reside.
Black women and women with diabetes, hypertension, infection, fewer than three prenatal care visits, previous preterm birth or interpregnancy interval less than six months were at increased risk of preterm birth, regardless of location of residence. Public insurance, maternal education less than 12 years, underweight BMI, and interpregnancy interval of five years or more were identified as risk factors only for women in urban residences. Women living in urban locations who were born in Mexico and who were overweight by BMI were at lower risk for preterm birth; WIC participation was protective for women in both urban and rural locations. Taken together, these findings suggest targeted place-based interventions and policy recommendations can be pursued. The preterm birth risk factors identified in these analyses are not unique to Fresno County: previous work has also shown that women of color, lower education, lower socioeconomic status, women with co-morbidities such as hypertension and diabetes, smoking, and short interpregnancy interval are at elevated risk of preterm birth.In Fresno County, however, we observed that these risks differ in magnitude. This is critical, as the percentage of women in each region with the risk factor can vary greatly.The degree of risk was mild – only a 1.1-fold increase in risk. However, 72% of the population giving birth in rural Fresno County is Hispanic, suggesting that focusing interventions reaching this population may provide the most impact. Similarly, Black women were at elevated risk of preterm birth regardless of location of residence. Since urban residences have the highest percentage of Black women and rural has the lowest , focusing prevention efforts for Black women in urban residences may be an effective approach. Others have found that with pre-pregnancy initiation of Medicaid , has been associated with earlier initiation of prenatal care,a factor that may reduce preterm birth rates.In addition, participation in the WIC program also has shown a moderate reduction of the risk of a small for gestational age infant and has been associated with reduced infant mortality in Black populations.
Fresno women from both urban and rural residences who participated in the WIC program were less likely to deliver preterm, while those women living in urban locations who were publicly insured through Medical coverage for delivery were at increased risk for preterm birth. Low income is a criterion for both public assistance programs, and over 32% of families in this region lives below the poverty line;it is apparent that social economic status is a complex risk factor for preterm birth. A key take away message from this study is that women who accessed prenatal care more frequently – three or more prenatal care visits – were less likely to deliver preterm. Fresno County may be able to improve preterm birth rates by addressing factors that encourage prenatal care access, which may include enrollment in Medi-Cal during the preconception period and increasing WIC participation. Identifying regions where a high percentage of women do not access three or more prenatal care visits may suggest locations for an intervention such as home visits or mobile clinic. Using a large administrative database allows for examination of rates and risks that would not be possible with other data sources. Despite these strengths, the study has some critical limitations. By design, the findings are very specific to one area of California and may not be as applicable to other areas of the state, country, or world. In fact, we recently conducted a similar study examining preterm birth risk factors by sub-type for all of California.Similar to the entire California population, we demonstrated increased risk of preterm birth for Fresno County women who were of Black race/ethnicity, who had diabetes or hypertension during pregnancy, or who had a previous preterm birth. However, Fresno County was different from the whole state in a few ways. Unlike the state of California as a whole, Hispanic women, women over 34 years at delivery, and underweight women in urban residences in Fresno County were at increased risk for preterm birth. Also, education over 12 years did not provide protection against preterm birth in any of the Fresno County residences, although higher education did provide protection when we looked at the whole state of California. These differences point to specific pathways occurring in Fresno County that may be distinct from the state as a whole, and demonstrate the value of place-based investigation of risk factors when examining a complex outcome such as preterm birth. Other residences may benefit from similar analyses to identify risk and protective factors that are important on a local level.
An additional limitation, as with most administrative databases, is that accuracy and ascertainment of variables is not easily validated. Previous studies of California birth certificate data suggests that race/ethnicity is a valid measure of self-identified race/ethnicity for all but Native Americans, and best obstetric estimate of gestation may underestimate preterm delivery rates.Previously reported rates of preterm birth in Fresno County are around 9.5% and was 8.4% overall in our population after removing multiple gestation pregnancies and pregnancies with major birth defects. Additionally, United States estimates for drug dependence/use during pregnancy is 5.0% to 5.4% and was only 2.5% in our population. This under ascertainment may mean that we are capturing the most severe diagnoses,vertical grow shelf potentially overestimating our risk calculations. Alternatively, under ascertainment also implies that drug users were likely in our referent population, which would underestimate our risk calculations. This examination of Fresno County preterm birth may provide important opportunities for local intervention. Several populations were identified as at risk, regardless of location of maternal residence, that deserve targeted interventions. Interventions focused on diabetes, hypertension, and drug or alcohol dependence/abuse across the county may be effective for preterm birth reduction. We identified several modifiable risk and resilience factors across the reproductive life course that can be addressed to reduce preterm birth rates. Given the complex clinical and social determinants that influence preterm birth, cross-sector collaborative efforts that take into account place-based contextual factors may be helpful and are actively being pursued in Fresno County. Ultimately, refining our understanding of risk and resilience and how these factors vary across a geography are fundamental steps in pursuing a precision public health approach to achieve health equity.The smoking prevalence among the general U.S. population is estimated to be 14% ; however, the prevalence of smoking among individuals experiencing homelessness in the U.S. is 70% . Smoking-caused cancer and cardiovascular disease are the leading causes of death among individuals experiencing homelessness . Previous studies estimating tobacco prevalence among homeless adults have focused exclusively on cigarette smoking. However, with the increasing availability and popularity of alternative tobacco products, defined as flavored and unflavored noncigarette tobacco products such as electronic cigarettes , cigars, or blunts , use of these products have increased among individuals experiencing homelessness . Between 51% and 68% of individuals experiencing homelessness have used one or more forms of ATP in the past 30 days . More than 50% of homeless smokers acknowledge high risk to health from non-cigarette combustible tobacco.
Studies have explored associations between ATP use and past year cigarette quit attempts and have found mixed results. In one study among homeless smokers, ATP use was not associated with readiness to quit or past-year quit attempts , whereas in a more recent study, ATP use was associated with a higher number of past-year quit attempts compared to cigarette only smokers . While these studies have contributed to tobacco research by showing that ATP use is common among individuals experiencing homelessness, there are still gaps in our understanding of patterns of ATP use and its consequences. Flavored non-cigarette tobacco use is increasing among the general population, and flavors are the primary motivators for initiation and continued use of ATPs . However, flavors are also associated with long-term addiction and difficulty with smoking cessation . We know of no studies to date that have examined flavored non-cigarette tobacco use among individuals experiencing homelessness. Individuals experiencing homelessness face substantial barriers to smoking cessation, and the use of ATP could make smoking cessation more difficult . However, some people may consider ATPs such as e-cigarettes as a lower risk alternative to cigarettes , potentially reducing harm . Given the varied uses for ATPs, there is a need for studies that explore how ATP use intersects with cigarette smoking behaviors among individuals experiencing homelessness. Moreover, ATP use is high among persons with mental health and substance use disorders and may be used to alleviate mental health and/or substance use cravings or may be a marker of severity of illness . ATP users have reported severe and pervasive externalizing outcomes comorbidity compared to cigarette-only users . ATP use may also increase the risk of developing substance use disorders compared to cigarette only or ecigarette only users . Mental health disorders such as depression, anxiety, bipolar disorder, schizophrenia, and post-traumatic stress disorder are common among populations experiencing homelessness and have also been shown to be associated with tobacco use . Moreover, substance use disorders are highly prevalent among homeless adults . Given the high rates of mental health and substance use disorders among people experiencing homelessness , examining use patterns of ATPs in this sub-population of smokers could be helpful with developing targeted interventions. In this study, we recruited a community-based sample of individuals experiencing homelessness who were current cigarette smokers to explore patterns of ATP use, including in-depth patterns of e-cigarette use, and association with past-year quit attempts. In addition to providing a larger sample size than previous studies to explore these associations, this study is also the first to report on the use of flavored tobacco and absolute perceptions of harm and addiction among individuals experiencing homelessness. Homeless adults are motivated to quit cigarette smoking and may use ATP as a cessation method ; therefore, we hypothesized that ATP use would be associated with increased past year quit attempts.We conducted a cross-sectional study of individuals experiencing homelessness who were recruited from eight sites, including emergency shelters, navigation centers , day-time referral programs, and community centers serving homeless adults in San Francisco, California . These sites primarily offered emergency shelter or referral services for individuals experiencing homelessness; no study site offered an on-site smoking cessation program. Individuals were eligible to participate if they were 18 years or older, had smoked at least 100 cigarettes in their lifetime, currently smoked cigarettes , were receiving services at the recruitment site, and were currently homeless as defined by the Homeless Emergency Assistance and Rapid Transition to Housing Act . We recruited participants between November 2017 and July 2018. We aimed to include participants who would express “typical” or “average” perspectives, and therefore recruited participants using typical case sampling .